WASHINGTON - On a day when President Donald Trump proposed $2.6 billion in new spending for border security, including $1.6 billion for a wall, the U.S. Customs and Border Protection chief told Congress that would-be border crossers are already being scared away by the administration's sweeping executive order on immigration.

"The message is out," said Ronald Vitiello, the border agency's acting deputy commissioner, told a Senate panel Tuesday. "The executive order calls for the end of catch and release."

Noting the dramatic reduction in border apprehensions in recent months, Vitiello testified that "We are seeing a historic shift in illegal crossings along the Southwest border."

Vitiello's testimony came at the invitation of Texas U.S. Sen. John Cornyn, who chaired a hearing on border security and immigration as Trump seeks more money from Congress to strengthen the border and boost deportations.

Some immigrant-rights activists denounced the law-enforcement focus of the hearing, saying that it appeared calculated to justify Trump's deportation sweeps and calls for costly new border security measures.

Related Stories

"We don't need more enforcement-only laws," said Frank Sharry, executive director of America's Voice Education Fund, which opposes Trump's immigration sweeps. "We need Congress to put a check on Trump's executive orders, to hold [the administration] accountable for its ruthless expansion of deportations… and to stand up to his idiotic border wall."

The Senate Judiciary hearing, Sharry added, "has all the authenticity of a Kabuki show."

Borders still 'porous'

As expected, Cornyn called for more border funding, saying "The fact is our borders are still porous, and we have not done a good enough job of making sure that the Department of Homeland Security has the resources you need in order to get the job done."

In the past, Cornyn has questioned whether a physical barrier is appropriate for the length of the U.S.-Mexico border. Like some other border-region Republicans, he has focused instead on the need for technology, law enforcement and infrastructure improvements.

Those kinds of improvements, including sensors, aerial surveillance and communications equipment, make up less than half of Trump's $2.6 billion request for the border.

But according to Vitiello, the word seems to be spreading about tougher interior immigration enforcement, including Trump's well-publicized raids, many more now involving people with no criminal past.

"We have seen indications that individuals' perception of their ability to remain in the United States after illegal entry has been affected by recent policy changes," Vitiello said. "Individuals who might seek to enter the country through unlawful channels do not want to invest significant resources only to be turned around at the border or removed soon after they arrive in the United States."

The number of illegal border crossers dropped 30 percent from February to March, which was also down 64 percent from the same time last year, according to new Border Patrol figures. The drop, Vitiello said, comes amid the same conditions of poverty and violence in Central America, the source of an increasing number of illegal immigrants.

"Push factors creating a demand for both legal and illegal immigration to the United States remain fairly constant for Latin America populations and Eastern Hemisphere populations," he testified. He noted that while more than 16,000 family units were apprehended at the border in December, only 1,125 were caught in March.

Democrats have criticized Trump's priorities on the border, citing both the new data on illegal border crossings as well as data showing zero or negative net growth in the nation's population of illegal immigrants.

'Layered' defense

Trump's new request to fund a wall - a central promise of his campaign - also has become a symbol of Democrats' opposition to his budget, which emphasizes military and national security spending while making massive cuts in domestic safety net programs.

"Putting taxpayers on the hook to pay for it is just the latest brick in a wall of broken campaign promises," said San Antonio U.S. Rep. Lloyd Doggett. "If we are going to pour billions into concrete, it ought to be an investment in ourselves, rebuilding our crumbling infrastructure. Spending billions more locking up immigrant families escaping violence isn't making America great or safe."

New budget documents released Tuesday show that the $1.6 billion for wall construction in Trump's 2018 budget would pay for 32 miles of new border wall and 28 miles of levee wall along the Rio Grande Valley. The money also would pay for 14 miles of new border wall to replace fencing in San Diego. Department of Homeland Security officials say those sites are priority areas where apprehensions are the highest along the Southwest Border.

Much of the rest of the new border spending, more than $975 million, would go to tactical infrastructure and border security technology, including sensors and radios, to provide a "layered" defense at the border. Trump's budget also would provide another $100 million to hire 500 new Border Patrol agents.

Another $109 million would go toward cargo scanners at border crossings and ports of entry, including technology that can detect materials that pose potential nuclear and radiological threats.

The new spending would come on top of some $1.6 billion Congress approved for border security through September, though none of that can be used for a wall. But whatever happens with Trump's 2018 budget, Vitiello said Trump's new arrest and detention orders are being felt.

"We have the laws in place to secure our borders," he said, "and we are enforcing them."

Kevin Diaz came to the Houston Chronicle in February 2014 with more than a decade of experience covering Washington. Before that, he was the chief Washington correspondent for the Minneapolis Star Tribune, where he got his start in journalism in 1984 as a night cops reporter. During his tenure in Minneapolis, he won awards for his coverage of gang crime and city hall. He also taught public affairs reporting at the University of Minnesota, where he received his Master’s. After a stint at the Washington (D.C.) City Paper, Kevin went back to the Star Tribune, where he won national awards for articles on globalization and immigration. He also covered the 9/11 terrorist attacks from Washington and New York. Born and raised in Italy, Kevin has reported from Italy, Brazil, Mexico, and Cuba, where he covered Jesse Ventura’s 2002 trade mission. In 2003, he filed daily Iraq War dispatches for McClatchy Newspapers from the U.S. Central Command in Qatar. In 2006, he covered the presidential election standoff in Mexico. He also has covered Washington for the Anchorage Daily News and the Idaho Statesman.